Hi

I know how to create Send Connectors in Exchange, but I am confused the mail flow "between SEND connector and recipient (let say gmail.com)". Consider if I have configured SEND Connector to use DNS....

I want to know which service will be used to contact DNS on internet to check MX.. In short I want to know, WHO will contact DNS?

Thanks in advance...

I believe Exchange will query the DNS servers configured on that server's NIC, so whatever you have configured there is what Exchange will use. Essentially Exchange does the lookup using the same mechanism that anything else running on that server uses to resolve DNS.

Thanks for reply Keith...

Correct me if I am wrong.. So Exchange will query local DNS and it will not find any MX for domain let say (Gmail.com) and hence query will be redirected to Internet DNS for searching MX..

Right?

if you have any article explaining the same, please share that with me. it will be a great help!!!

Best regards,

Tawsif Mulani

No, you're thinking of "local" DNS as being the local installation of the DNS Server role on that server I assume?

Exchange will query whatever you have configured as your DNS servers within your NIC settings, IF those point to your DNS Server installation on the local machine (if you have one), then it may query those, but that's a separate step in the lookup. DNS Server (that serves results) and DNS Client (that does lookups and caches replies, and which is found on ALL windows machines) are two completely different services.

Whatever DNS server your query goes to (eg as determined by the settings on your NIC), the DNS server will return a result providing the relevant MX records. How the DNS server provides that information is a completely separate process, but if it doesn't already know the answer (eg it's local or cached) then it will then connect to the internet to do the lookup, and then once completed it will return the result to Exchange.